Conventionally, an X-ray generator used for X-ray inspection performed by irradiating X-rays to an object to be inspected has an X-ray tube to an anode electrode and a cathode electrode, and a tank for housing the X-ray tube and having insulation oil contained therein. In the X-ray generator, by supplying a predetermined voltage to the anode electrode and the cathode electrode, electrons are emitted from the cathode electrode whereby the emitted electrons collide with the anode electrode to generate X-rays.
In such an X-ray generator, abnormal discharge (discharge which can be an obstacle to inspection) may occur in the X-ray tube or in the tank. Such abnormal discharge includes abnormal discharge caused by the lapse of service life and abnormal discharge, caused by the structure of the X-ray tube. The abnormal discharge caused by the lapse of service life can occur inside the X-ray tube or inside the tank outside the X-ray tube due to deterioration of vacuum degree and deterioration of insulation performance such as insulation oil. The abnormal discharge caused by the structure of the X-ray tube occurs inside the X-ray tube due to the fact that the electrons emitted from the cathode electrode stay in the X-ray tube without colliding with the anode electrode or the like, and has little relevance to the lapse of service life.
When abnormal discharge caused by the lapse of useful life occurs, using the apparatus in such a state will lead to a decline in the inspection accuracy. Therefore, it is desirable to inform the administrator for prompting him to perform maintenance such as replacing the X-ray tube. For example, Japanese Patent Application Laid-Open No. 2001-145625 discloses a technique in which when abnormal discharge in the X-ray tube occurs for a predetermined number of times or more within a fixed period, operation of the apparatus is terminated and a predetermined message is displayed on a display.